Blaine is wearing special boots that keep his blood pumping through his legs; his chest and arms are coated with a special gel (the same kind that people wear when they swim the English Channel), and he is using a catheter.
If his face presses up against the ice (as mentioned above), his people will try to wake him. The method they decided on was to tug on his catheter.
Also, as others have mentioned, it’s not a magic trick. It’s an endurance test that is mainly being used as publicity for the ABC special that will follow his coming-out of the ice block.
Blaine is definitely not Houdini. Houdini became world famous without the benefit of TV or the internet or any of the other modern-day vehicles for smart PR and slick marketing. As for the ‘fraud’ element, well, it’s just for entertainment. But yeah, Blaine is a magician, and what you think you see is not what’s really going on. A few pointers. The very thick ice is not there to freeze Blaine. It’s there to stop anyone getting too close to him to examine what’s really going on. People think they can see Blaine moving about, because that’s what they’ve been told they can see. Does any recent visitor to Disney think they actually saw Lincoln? Why can’t people TALK to Blaine? Wouldn’t that relieve the bordeom for him a little?
This is not about enduring coldness for a long period. It’s about marketing and getting people to tune into a TV show.